A History in Calculators

Justin Zobel

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Texas Instruments TI-95 Procalc; Tandy EC-4026

While packing for a house move, I found calculators in drawers, boxes, cupboards. Almost every calculator (or organiser) I'd ever owned. All of these were machines I'd had since they were new, carefully hoarded away over my entire lifetime ... just in case. These calculators reflect the evolution of the technology, from first emergence as a mass-market product to near-terminal decline; the calculator is almost obsolete now, but once was essential. So many calculators. Here they are.

In 1987, an acquaintance doing a PhD on crop yields asked if I could help with a calculator being used by her team. This machine, a TI-95 programmable, was a descendant of the TI-58, far richer and also better designed, and the researchers wanted to use it in the field. Part of the project design was use of a small thermal printer, to allow data to be captured in a systematic way while working away from campus. In that period, before laptops, such a calculator was the only portable tool that could be used for computation. I agreed to help so long as I could keep a duplicate machine in my office, and another TI-95 was bought and loaned to me.

These researchers eventually requested 10 or 12 programs, some of them reasonably complicated, and for the first time I programmed a calculator for a serious purpose. My acquaintance would occasionally drop by for a change to the code, or phone in from somewhere remote and ask for support. Over time these calls became increasingly rare. At some point I put the TI-95 away in a file box with other unused gear (some computer tapes and floppy disks, a deck of punch cards, and old manuals) rather than risk losing or damaging it, and then forgot about it.

When I came across the TI-95 again, during an office move in the 2000s, it still worked and even the thermal paper was still useable. Over the decade after this machine was made the emergence of laptops and organisers would make programmable calculators largely obsolete, but in 1987 there were many applications for which they were the only choice.

The last calculator I bought — prior to 2018 — was a Tandy, in 1991. Tandy was an Australian rebranding of Radio Shack; this calculator was a rebranding of a Casio model. I bought it because I wanted a portable device to run simple calculations, in effect stored programs of a few dozen steps. (Laptops then were primitive: limited power and memory, and heavy and unreliable.) While visiting my parents, for example, I could use it to work on research problems, or even run an elementary simulation. After a year or two, though, I only used it for more basic tasks such as checking grant budgets.

This Tandy was my desktop calculator until 2018, on its original battery. It is the only one of my calculators whose case has deteriorated; as the photograph shows, a laminated coating has peeled away. In the middle of 2018 I bought a new calculator, but only because of this project of documenting my collection; with even my newest calculator dating from 1991 and officially vintage, it seemed wrong to keep using it, especially as it was visibly aging. And it seemed strange to have no calculator at all.

The 2018 purchase was a new HP-35S calculator, which essentially repeats the functionality of high-end 1980s models (but cost only $60 online). I could instead have bought a new Casio, the 5800P, which is a straightforward update to the Tandy and adds little to it. After 30 years — it was introduced in 1989 — it is still more or less the state of the art for a scientific calculator.

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Last updated July 2018.

This webpage was created by Justin Zobel. All images are Copyright© University of Melbourne. Photography by Lee McRae.